Spark plug



Nov, 3, 1936. w E, ETTERMAN 2,059,257

- SPARK PLUG Filed Oct. 15, 1934 2 Sheets-Sheet 2 JWy;

v Inventor aiya/vnd fr tainted Nov. 3;, 1936 1 Claim.

This invention appertains to new and useful improvements in internal combustion engines and more particularly to a novel spark plug construction. The invention relates even more particularly to a spark plug having a valved vconduit for admitting air to the interior of the combustion chamber of an internal combustion engine with which it is associated.

An important object of the present invention is to provide a spark plug of the type specified having air passing means controlled by a check valve operative to admit air upon the intake stroke of the piston of the engine whereby a stream of air is impinged upon the sparking parts of the plugs so as to clean them and prevent the formation of carbon thereon and the consequent fouling thereof.

Another important object of the invention is to provide a spark plug whereby air is introduced into the combustion chamber of an engine so as to scavenge the combustion chamber of oil accumulations and carbon, and by this means, in conjunction with the cleaning of the sparking parts, to increase the efficiency and economy of operation of the engine. I

Still another important object of the present invention is to provide a spark plug construction as described above,'whereby the sparking points thereof are kept clean and cool by the impinged stream of air, thereby prolonging the useful life of the spark plug and its greatest efficiency, resulting in continued perfect combustion in the engine.

Other important objects and advantages in the invention will become apparent to the reader of the following specification.

In the drawings:

Figure l is a longitudinal sectional view through the spark plug.

' Figure 2 is a cross sectional view taken substantially on line 2 2 of Figure l.

Figure 3 is an end elevational view of the inner end of the plug.

Figure 4 is a perspective view of the hollow electrode. I

Figure 5 is a perspective .view of the air filtering element.

Figure 6 is a side elevational view of the threaded bushing.

Figure 7 is an end elevational view of the bushing shown in Figure 6.

Referring to the drawings wherein .like numerals designate like parts, it can be seen that numeral i5 generally designates the body portion of` the spark plug construction. This comprises the usual wrench grip It below which is Vthe cylinder engaging annulus l1 from which depends the reduced exteriorly screw-threaded skirt i8 ior projecting into the combustion. chamber'` On one side of the lower edge of the skirt it is the usual electrode i9 projecting toward the center of the opening in the skirt. A conventional type of composition insulator 2li is engaged with the body portion of the sparkplug in the usual manner, and is retained and assembled by means of the annular nut 2l engaged in the opening in the upper part of wrench' gripping portion it.

All parts of the spark plug thus far described may be conventional, except for certain features of the insulator 20. The invention is particularly concerned with the construction of the insulator 20 and its electrode 23, and the manner in which the electrode 23 is associated with the outer electrode i9.

The insulator 20 is provided axially throughout its length with an opening 43 in which is disposed a tubular electrode 23. An enlarged bore 24 is provided in the insulator 20 from the top down to within the hub portion thereof as designated 20 at 50, and reduced therefrom down to the lower end thereof. The electrode 23 is disposed and recessed within the bore 24 described in the insulator 20. The upper portion of the electrode 23 has an enlarged bore 25 with a reduced bore 4l in the lower portion thereof. Within the enlarged bore 25 rests a helical spring 26, on a shoulder 45 provided therein, having a check-ball 21 in position on the top of the helical spring 2B whichv comprises the check valve assembly and secured in position by a cushion block or threaded bushing 28. The valve seat 28 is threaded exteriorly as at 23 tothe top from about one-third of the distance up from the lower end thereof, being tubular throughout its length with the lower third portion 48 reduced slightly in diameter to fit within the bore 24 of the insulator 20 enabling that part 32 of the lower end thereof receding from the extremity 30, occasioned in providing the concavity or valve seat 3l, to rest on the top of the electrode 23 and make contact between it and the terminalA 38 as well as securing the 'entire assembly in position when sealed with cement in that portion of the upper end 41 of the insulator 20 which has been interiorly threaded to receive the cushion block or threaded bushing 28. In the upper portion of the valve seat 28 is provided a recess 34 interiorly threaded to receive a tubular boss 35 exteriorly threaded throughout its length which secures a ne mesh screen disk 35 placed on the bottom of the recess 34 for-the purpose of preventing foreign particles from entering the cylinders. The tubular boss 35 is removablelin the event the screent requires cleaning. The valve seat 23 and the tubular boss 35 are provided with slots, being 33 and 3l respectively, in the top ends enabling such parts to be placed into position or for removablepurposes in rconnection with 35. The threaded upper portion of the boss 35 receives the terminal 38 which is tubular throughout and threaded interiorly in the lower portion thereof. The check-ball assembly provides operable means of communicating ithe upper tubular section 22 above such with the lower tubular section 49 of the electrode 23. The tension of the helical spring 26 need only be suilcient to maintain the check-ball 21 seated under normal conditions.

When the plug is installed on an engine, the down stroke or intake stroke of the piston will create a suction in the tubular electrode 23 such as will unseat the check-ball 21 and draw through the top of the plug a volume of air into.the combustion chamber. It will be obvious, since the terminal of the electrode I9 is placed at the opening of the lower end i9 of the tubular electrode 23, that the incoming air will impinge upon the terminal oi the electrode ld and also create a cleaning agitation about the lower end i9 of the electrode 23. It will be observed that the lower extremity of the electrode 23 projects slightu ly below the lower end of the insulator 2i). The main or upper portion of the electrode 23 is spaced from the bore of the insulator 2i) as indicated at 40 and the lower portion of the electrode 23 is spaced from the insulator as indicated at 42 and the insulator 20 is spaced from the shell as indicated at 4G to allow for the expansion of these parts of the electrode due to heat when the plug is in operation.

It will be observed that the arrangement is such that when the stream of air is produced. in the manner described, that air will be introduced into the combustion chamber and in its passage thereinto will cleanse and cool the electrodes of the spark plugs, whereby to produce the effects sought herein.

Though I have shown and described herein a preferred embodiment of the invention, it is to be clearly understood that I do not desirel to limit the application of the invention thereto, and any change or changes'may be made in material and structure and arrangement of parts, within the spirit of the invention and the scope of the subjolned claim.

Having thus described the invention, what is vclaimed as new is:

A spark plug comprising a, conductor shell, an insulation core for the shell, said core being provided with a bore therethrough, a hollow electrode extending in the bore and being provided with an enlarged upper portion, said core being provided with internal threads at its upper end, a threaded block for disposition into the said threaded upper portion of the core, said block having an opening therethrough and being of current conductive material, a terminal connector at the upper end of the block also provided with an opening therethrough communicating with the opening through the block, said opening through. the bushing communicating with the enlarged upper portion of the hollow electrode, the lower portion of the hollow electrode being provided with a sparking electrode terminal extending therethrough, said shell being provided with an electrode projecting to a position in sparking relation to said electrode terminal, said block at its inner end being provided with a valve seat, a coiled compressible spring in the enlarged upper portion of the hollow electrode, said spring being provided at its upper end with a ball and adapted to normally maintain the said ball engaged in the said seat.

WILLIAM E. IE'I'rERMAN. 

